Pág. 16
AUDIMAX 362
SOLIDYNE
b) Replace the audio generator at the processors
Left input for audio program (music or voice).
Please carefully take note of this peak-to-peak
value; let name it Xpp.
c) Disconnect the audio program from the LEFT
input and disconnect the ground of the test
point
TP1
. Then, the 19 Khz pilot tone will
appear.
d) With the oscilloscope measure the peak-to-
peak value of the 19 Khz pilot tone; let name it
Ppp.
The percentage level of pilot tone will be:
Pilot Level [%] = 100.Ppp / Xpp
e) This value must be between 9 to 11 %
Otherwise, please contact your Solidyne dealer.
NOTE:
If you have a
Solidyne VA16
modulation
monitor or BELAR FMS-2 measurement set, you will be
able to measure pilot tone level from on-air
transmission.
4.3
Pilot Phase adjustment
This method is an
absolute system
not dependent
from the calibration of the Modulation Monitor.
You will need a very good DC-20 Mhz
oscilloscope (Tektronix preferred) with vertical
10x undistorted span. Proceed:
a) Change the
PHASE jumper
(JF1) from the
Normal “N” position to calibrate “C” position.
b) Input a sine wave generator at 1 KHz, +4 dBm,
at Left Channel of the audio processor. Adjust
the level of wave generator to get 4 Vpp MPX
output.
c) Connect the oscilloscope to the MPX output
in
mode DC.
Use the sine wave output of audio generator,
to synchronize the oscilloscope sweep. Adjust
the sweep to 5 uS/Div. Modify with trigger
level, the center of the wave in order to have it
centered at screen.
Adjust vertical sensitivity to 50 mV/Div. You
must get a signal like FIG-2.
If not, you must do a slight change in the
frequency knob of the audio generator in order
to avoid integral multiplication factors that do
not allow you to appreciate the correct image.
FIG.2
Pilot Phase 10X
Calibrate the
P10
Phase Control to get zero
phase error. The phase error is indicated by
the tilt of the imaginary line between H1-H2
points. When this line is full horizontal, the
phase is correct.
e) Change the phase calibration jumper to
NORMAL mode ( “N” position).
4.4
Channel Separation
Since the stereo coder uses a digital technology,
there is not any kind of adjustments controls for
stereo separation. A good measurement set like
the BELAR (USA) model FMS-2, will be needed.
If you do not have an excellent measurement set,
please do not intend this measure.
Note :
This measure must be done with stereo coder
inputs disconnected from audio processor. Then the
jumpers JL & JR must be open.
a) Connect the BELAR measurement set to the
MPX output connector.
b) Check the PHASE mode of the Belar. You
must get at least – 65 dB rejection of 19 KHz
pilot tone. If not, please make the Belar
calibration procedure of PHASE (see Belar
manual)
c) Connect a sine wave generator at 400 Hz, 1V
RMS
to
the
Left
Input
(
JL
).
Leave
disconnected the right input
JR
.
d) Measure channel separation at the Belar. Right
channel. It will be better than 60 dB
e) Now, connect the sine wave generator, at the
same frequency and level, to the Right
Channel (pin
JR
).
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